Propane-piezoelectric ignition system

ABSTRACT

A spark igniter and flame flash-back system for a stove, which system is mounted on the grease tray of the stove. Flash-back tubes are mounted on the tray and serve to funnel fuel from the burners to the igniter. The igniter is of the piezoelectric type which produces a spark. The igniter primary or hot electrode is connected to the piezoelectric crystal and is held in place on the grease tray by the flash-back tubes which also include fuel deflectors to deflect the fuel flow toward the hot electrode. The deflectors also serve as the secondary electrodes to which the spark jumps from the hot electrode.

limited States Patent [1 1 Lapins et a1.

PROPANE-PIEZOELECTRIC IGNITION SYSTEM [75] Inventors: Daniel W. Lapins, DeKalb; Carl E.

Finley, Sycamore, both of I11.

[73] Assignee: Olin'Corporation, New Haven,

Conn.

[22] Filed: Nov. 24, 1971 [21] Appl. No.: 201,732

[52] US. Cl. 431/191 [51] Int. Cl. F24c 3/10 [58] Field of Search 431/191, 192, 193, 431/194, 255, 266; 126/39, 38

[56] References Cited UNITED STATES PATENTS 3,523,747 8/1970 Gross et al 431/192 2,682,303 6/1954 Reinhart 431/191 2,896,704 7/1959 Aleweld 431/255 4/1937 Laghetto 431/192 X 2/1967 Gjerde 431/266 Primary ExaminerEdward G. Favors Attorney-William W. Jones et al.

[5 7] ABSTRACT A spark igniter and flame flash-back system for a stove, which system is mounted on the grease tray of the stove. Flash-back tubes are mounted on the tray and serve to funnel fuel from the burners to the igniter. The igniter is of the piezoelectric type which produces a spark. The igniter primary or hot electrode is connected to the piezoelectric crystal and is held in place on the grease tray by the flash-back tubes which also include fuel deflectors to deflect the fuel flow toward the hot electrode. The deflectors also serve as the sec ondary electrodes to which the spark jumps from the hot electrode.

5 Claims, 4 Drawing Figures PROPANE-PIEZOELECTRIC IGNITION SYSTEM This invention relates to a spark igniter for use with a combustible fuel appliance such as a camp stove, and more particularly to the mounting of such an igniter on the appliance.

The use of piezoelectric or other type spark igniters to light the burners on portable camping stoves is generally known in the prior art. Various arrangements have been proposed for mounting such igniters on the stoves. It has been proposed to mount the igniter on the stove so that the spark gap is closely adjacent to the burner so that fuel fed through the burner is ignited and burned in close proximity to the spark gap. This arrangement is, however, unsatisfactory since more than one spark gap must be provided for a multiple burner stove, thus greatly increasing the cost of the stove. Furthermore, the proximity of the burner flame to the spark gap results in undesirable carbon build-up in the spark gap which carbon build-up must be removed lest it close the spark gap and render the igniter inoperable.

Yet another arrangement has been proposed which includes the use of a fuel and flame flash-back tube extending from the perimeter of burners to the spark gap portion of the igniter. This arrangement mounts the igniter on the stove base and the flash-back tube also on the stove base or on the grill. Fuel from an open burner is transmitted from the tube to the spark gap which is then actuated to ignite the fuel in the tube. The flame then flashes back through the tube to the burner to ignite fuel issuing from the burner. This latter arrangement has proven functionally adequate but rather complicated and costly to assemble. This invention relates to an improved assembly utilizing the latter arrangement and greatly reducing the complexity of assembly.

The stove of this invention includes a grease tray which overlies and protects the basal portion of the stove. The grease tray is readily removable from the stove base without the use of anyspecialized tools. The hot electrode of the igniter is mounted in an insulator which in turn is mounted in an aperture in the grease tray. Fuel flash-back tubes are mounted on thegrease tray preferably through the use of a tab and slot arrangement. The flash-back tubes overlap the insulator and hold the latter in place on the grease tray. The flash-back tubes include deflector portions which extend downwardly through the fuel passage toward the hot electrode. The deflectors cause the fuel flowage through the flash-back tube to be deflected toward the hotelectrode. The deflectors also serve an additional function inv that they terminate a short distance above the hot electrode and serve as the secondary electrode in the spark gap. The other end of each of the flashback tubes terminates adjacent to each of the burners on the stove. Thus, when one of the burners is opened and fuel issues therefrom, the fuel passes through the particular flash-back tube toward the deflector. The fuel is then caused to flow toward the hot electrode by the deflector. The ignition system is then actuated to cause a spark to jump from the hot electrode to the deflector which spark ignites the fuel in the flash-back tube. The flame then flashes back through the tube to ignite the open burner.

It is, therefore, an object of this invention to provide an ignition system for a hydrocarbon burning appliance which ignition system utilizes a spark to light the appliance.

It is a further object of this invention to provide a system of the character described utilizing a support member readily removable from the remainder of the appliance and which support member carries the hot electrode of an electrical igniter.

It is yet another object of this invention to provide a system of the character described which includes burners on the appliance which are spaced apart from the sparking source and which utilize flash-back tubes mounted on the support to carry fuel from the burner to the spark source and also carry flame from the spark source to the burner.

It is an additional object of this invention to provide a system of the character described wherein the flashback tubes include fuel deflectors which deflect the flow of fuel toward the hot electrode of the igniter.

It is yet another object of this invention to provide a system of the character described wherein the deflectors serve as the secondary electrode for the igniter.

Other objects, advantages and features of the inven tion will become apparent to one skilled in the art from the following detailed description of a preferred embodiment of the invention taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a perspective view of a preferred embodiment of the invention in the form of a portable camp stove utilizing propane fuel;

FIG. 2 is a perspective view of the grease tray portion of the stove of FIG. 1 showing the flash-back tubes and igniter insulator mounted thereon;

FIG. 3 is a vertical sectional view taken along lines 3-3 of FIG. 2 showing the manner in which the flashback tubes hold the hot electrode assembly in place on the tray; and

FIG. 4 is a vertical sectional view taken along 4-4 of FIG. 3.

Referring now to FIG. 1, a preferred embodiment of the invention'in the form of a portable camp stove is shown. The stove includes a base portion 2.on which are mounted a pair of burners 4 and 6. A fuel conduit 8 is carried by the stove base 2 and is connected to a pressurized cannister 10 of liquid propane fuel. In the conventional manner the fuel flows in a gaseous state through the conduit 8 and thence through valves (not shown) to the burners 4 and 6. Control knobs I2 and 14 are connected to the valves to control the flow of fuel to the burners 4 and 6 respectively. A conventional piezoelectric current-generating device (not shown) is mounted on the base 2 and is actuated by a push button 16. A grease tray 18 is mounted on the base 2 and serves to protect the base 2 and internal working parts contained therein from becoming fouled by cooking residue. A pair of flash-back tubes 20 and 22 (identical and interchangeable) are mounted on the tray 18, as is a grill 24, the latter of which overlies the flash-back tubes 20 and 22 and the burners 4 and 6. It is noted that the grill 24 is mounted on the tray 18 in such a manner so as to be easily removed therefrom by simple upward lifting without the use of any specialized tools. Similarly, the tray 18 is preferably mounted on the base 2 so as to be easily removable therefrom. In this manner the component parts of the stove may be easily cleaned in the field without the use of any specialized tools.

Referringnow to FIG. 2, details of the tray 18 are shown. The tray 18 includes a central downwardly recessed portion 26. A pair of burner openings 28 and 30 are positioned at opposite sides of the recess 26 to accomodate the burners 4 and 6 respectively. An annular ridge 32 and 34 is disposed around each of the openings 28 and 30 respectively to protect the burners from grease or any other contaminant which may settle in the recess 26. It will be noted that each of the flashback tubes 20 and 22 extends outwardly from a sparker indicated generally by the numeral 36 to the respective burner apertures 28 and 30.

Referring now to FIG. 3, details of the mounting of the sparker 36 are shown. The sparking device 36 includes an electrode insulator button 38 which is positioned in an aperture 40 in the tray 18. The button includes an enlarged head portion 42 which rests on the tray and a reduced stem portion 44 which extends through the tray aperture 40. A passage 46 extends through the insulator button 38 with the upper portion of the passage 46 being enlarged to form a well 48. The primary or hot electrode 50 is positioned within the insulator passage 46, the electrode 50 having an enlarged head portion 52 which is positioned in and rests on the bottom of the insulator well 48 and a reduced stem portion 54 which extends through the insulator passage 46, and the lower portion of which is preferably threaded. An electrical conductor 56 is connected to the hot electrode 50 by means of a nut 58 which also secures the electrode 50 to the insulator button 38. Each of the flash-back tubes 20 and 22 includes a pair of downwardly extending tabs 60 and 62 respectively (only one shown). The tabs 60 and 62 extend into complimentary slots 64 and 66 respectively which are formed in the tray 18. The tabs 60 and 62 are bent outwardly as shown in FIG. 4 to secure the tubes 20 and 22 to the tray 18. The inner ends of the tubes 20 and 22 are undercut as at 68 and 70 respectively with the undercut tube portions 68 and 70 closely overlying the insulator head 42 so as to restrict upward movement of the insulator button 38. In this manner the insulator button 38 is held in place on the tray 18 by the flash-back tubes 20 and 22. Each of the flash-back tubes 20 and 22 includes a fuel deflector 72 and 74 respectively in the form of a tab which is bent downwardly from the top of each tube toward the hot electrode 50. The free ends 76 of the deflectors 72 and 74 are closely adjacent to each other and are spaced apart from the hot electrode head 52 a predetermined distance with that predetermined distance forming the spark gap 78 of the sparking device. It will be noted from FIG. 4 that the interior of the flash-back tubes 20 and 22 forms a channel which is sharply reduced in area by the deflectors 72 and 74.

The device operates as follows: assuming that one wishes to ignite the burner 6, the control knob 14 is turned so as to permit fuel to flow from the cannister to the burner 6. Fuel thus issuing from the burner 6 flows into the tube 22 and flows therethrough until impinging the deflector 74 at which time the fuel is caused to flow through the spark gap 78. The igniter button 16 is then pushed to cause the piezoelectric element to send a current through the conductor 56. The electric current is thus transmitted to the hot electrode 50 and a spark is caused to jump across the spark gap 78 to the secondary electrodes 76. The spark jumping the spark gap 78 ignites the deflected flowage of fuel and the resultant flame is then flashed back through the tube 22 to ignite the fuel issuing from the burner 6. In this manner ignition of the burner 6 is established.

It will be readily appreciated that assembly of the unit is quite simple and quite simply and easily accomplished. The hot electrode is inserted into the insulating button which is then in turn inserted into the aperture in the grease tray and the conductor is then secured to the hot electrode. The flash-back tubes are then mounted on the tray so as to hold the insulator button in place and the tray is then mounted on the stove base. By securing both the hot electrode and the secondary electrode to the same support member the dimension of the spark gap is closely controlled and remains constant during useage of the appliance. The use of deflectors insures that the fuel will pass through the spark gap and be ignited and not bypass the igniter. Furthermore, the use of the deflectors as the secondary electrode permits a cost saving by eliminating the requirement of a separate secondary electrode in the system.

Since many changes and variations of the described embodiment of the invention may be made without departing from the inventive concept it is not intended to limit the invention otherwise than as required by the appended claims.

What is claimed is:

1. In a hydrocarbon-fueled appliance having burner means for combustion of the fuel, an ignition system comprising:

a. support means mounted on the appliance:

b. spark-producing means mounted on said support means remote from the burner means, said sparkproducing means being electrically actuated and including a source of electrical current and a primary electrode connected to said electrical current source, and a secondary electrode spaced apart from saidprimary electrode to provide therewith a spark gap;

c. tubular means secured to said support means and extending from the burner means to said sparkproducing means, said tubular means being operable to conduct fuel issuing from the burner means to said spark-producing means for ignition of said conducted fuel, and said tubular means further being operable to transmit flame resulting from ignition of said conducted fuel to the burner means to ignite fuel issuing therefrom; and

d. deflector means traversing said tubular means to deflect the flowage of the conducted fuel toward said spark-producing means to ensure ignition of the conducted fuel, said deflector means forming said secondary electrode.

2. The system of claim 1, wherein said tubular means overlaps a portion of said spark-producing means to hold the latter in place against said support means.

3. In a hydrocarbon-fueled appliance having burner means for combustion of the fuel, an ignition system comprising:

a. spark-producing means mounted on the appliance and including a source of electrical current and a primary electrode connected thereto, said primary electrode being remote from the burner means;

b. tubular means secured to the appliance and extending from the burner means to said primary electrode, said tubular means being operable to conduct fuel issuing from the burner means to said primary electrode for ignition of the conducted fuel, and said tubular means further being operable to transmit flame resulting from ignition of said conducted fuel to the burner means to ignite fuel being positioned on said support means and remote issuing therefrom; and from the burner means; c. deflector means traversing said tubular means in t b l means secured to id u o t an d the area of said primary electrode, said deflector extending f the burner means to i Spark gap,

means being spaced apart from said primary elec- 5 trode a predetermined distance to provide a spark gap with said primary electrode, and said deflector means being operable to cause said conducted fuel to flow through said spark gap. 4. In a hydrocarbon-fueled appliance having burner 10 means for combustion of the fuel, an ignition system said tubular means being operable to conduct fuel issuing from the burner means to said spark gap for ignition of said conducted fuel, and said tubular means further being operable to transmit flame resulting from ignition of said conducted fuel to the burner means to ignite fuel issuing therefrom; and

comprising. d. said tubular means engaging a portion of said pria. Support means mounted on the appliance. mary electrode assembly to hold the latter in place b. spark-producing means including a source of elecagainst said pp means trical current connected to a primary electrode as- The System of Claim Wherem 531d Secondary sembly, and a secondary electrode spaced apart electrode is a deflector means traversing said tubular from said primary electrode assembly to provide a means to deflect fuel flowage into said spark gap. spark gap, said primary and secondary electrodes 

1. In a hydrocarbon-fueled appliance having burner means for combustion of the fuel, an ignition system comprising: a. support means mounted on the appliance: b. spark-producing means mounted on said support means remote from the burner means, said spark-producing means being electrically actuated and including a source of electrical current and a primary electrode connected to said electrical current source, and a secondary electrode spaced apart from said primary electrode to provide therewith a spark gap; c. tubular means secured to said support means and extending from the burner means to said spark-producing means, said tubular means being operable to conduct fuel issuing from the burner means to said spark-producing means for ignition of said conducted fuel, and said tubular means further being operable to transmit flame resulting from ignition of said conducted fuel to the burner means to ignite fuel issuing therefrom; and d. deflector means traversing said tubular means to deflect the flowage of the conducted fuel toward said spark-producing means to ensure ignition of the conducted fuel, said deflector means forming said secondary electrode.
 2. The system of claim 1, wherein said tubular means overlaps a portion of said spark-producing means to hold the latter in place against said support means.
 3. In a hydrocarbon-fueled appliance having burner means for combustion of the fuel, an ignition system comprising: a. spark-producing means mounted on the appliance and including a source of electrical current and a primary electrode connected thereto, said primary electrode being remote from the burner means; b. tubular means secured to the appliance and extending from the burner means to said primary electrode, said tubular means being operable to conduct fuel issuing from the burner means to said primary electrode for ignition of the conducted fuel, and said tubular means further being operable to transmit flame resulting from ignition of said conducted fuel to the burner means to ignite fuel issuing therefrom; and c. deflector means traversing said tubular means in the area of said primary electrode, said deflector means being spaced apart from said primary electrode a predetermined distance to provide a spark gap with said primary electrode, and said deflector means being operable to cause said conducted fuel to flow through said spark gap.
 4. In a hydrocarbon-fueled appliance having burner means for combustion of the fuel, an ignition system comprising: a. support means mounted on the appliance; b. spark-producing means including a source of electrical current connected to a primary electrode assembly, and a secondary electrode spaced apart from said primary electrode assembly to provide a spark gap, said primary and secondary electrodes being positioned on said support means and remote from the burner means; c. tubular means secured to said support means and extending from the burner means to said spark gap, said tubular means being operable to conduct fuel issuing from the burner means to said spark gap for ignition of said conducted fuel, and said tubular means further being operable to transmit flame resulting From ignition of said conducted fuel to the burner means to ignite fuel issuing therefrom; and d. said tubular means engaging a portion of said primary electrode assembly to hold the latter in place against said support means.
 5. The system of claim 4, wherein said secondary electrode is a deflector means traversing said tubular means to deflect fuel flowage into said spark gap. 